All of the Apollo missions to fly to the moon carried a measure of risk.

But the final lunar landing, Apollo 17 in December 1972, also had a distinction of being risqué — thanks to a prank that brought together a G-rated cartoon and an R-rated photo.

Apollo 17 crewmates Gene Cernan, Harrison Schmitt and Ron Evans were on their way to the moon, when at some point they turned the page of their flight plan to discover not the next step to be carried out on the mission, but a full-color pin-up ripped from the pages of Penthouse magazine.

There, “spread out” before them, was Helen Caunt, Penthouse’s “Pet of the Month” for October 1971. And the Road Runner. And Wile E. Coyote.

What?

“I suppose it was payback for the prank we pulled, as the Apollo 14 backup crew, on the Apollo 14 prime crew,” wrote Cernan in a letter describing the centerfold in July 2016.

A year before he became the “last man on the moon,” Cernan conspired with his colleagues to egg on the Apollo 14 crew by hiding a comical version of their mission patch aboard their spacecraft. Once in space, Alan Shepard, Ed Mitchell and Stu Roosa found the embroidered emblems popping out from behind locker dockers and other nooks inside the capsule.

The patches featured the Looney Tunes characters in a design that implied the backup crew — the Road Runner — had beaten the prime crew, represented by an aging Wile E. Coyote, to the moon. Inscribed along the top border of the insignia was simply, “Beep Beep.”

“There’s more badges …beep, beep, beep all over the place,” Shepard said a little over an hour into the Apollo 14 mission.

“He who laughs last,” replied Roosa.

“I’m hell of a lot happier that we’re flying and looking at their patches, rather than the other way around,” said Shepard.

But Roosa, apparently, wasn’t done laughing.

As the backup to Evans on the Apollo 17 mission, it was Roosa’s idea to sneak the photo into the flight plan. And just so that was clear — and Ms. Caunt’s “features” were not — he taped illustrations of the the Road Runner and Wile E. Coyote over the model’s more sensitive bits.

The cartoon showed the coyote grasping the bird by the neck with the inscription, “Beep, Beep Yuras!” (“Beep, Beep Your Ass!”)

“It was a great gag and brought the whole practical joke full circle,” wrote Cernan, who retained the pin-up as a memento of the mission.

“This Penthouse centerfold represents one of the rarest and more ‘interesting’ Apollo artifacts of the Apollo 17 mission,” Cernan wrote, “and was an example of the culture and camaraderie exhibited by astronaut corp (sic) of the 1960’s.”

And that, as they say, is all, folks!

This artifact is a part of our April 2017 Space Exploration and Aviation auction. Click here to preview this lot or click here to preview the auction.

On March 13, 1969, Apollo 9 returned safely to Earth after a ten-day test of the Command Service Module (CSM) and Lunar Module (LM). This was the first manned flight of the LM, and proved it worthy of manned spaceflight.

In our upcoming April Space & Aviation sale, we will offer one of the flashlights carried on the mission from the collection of Lunar Module Pilot Rusty Schweickart. The flashlight is signed and flight-certified on the body twice in black felt tip, “Flown on Apollo 9, Rusty Schweickart,” and is accompanied by a letter of authenticity from Schweickart.

The auction opens for bidding on April 13, and will close on April 20, 2017.